Effectiveness of ridge vent to wind-driven natural ventilation in monoslope multi-span greenhouses

Abstract

A large eddy simulation (LES) model and wind tunnel experiments were used to investigate the wind-driven ventilation of monoslope greenhouses with ridge vents. The accuracy of the numerical simulation was verified by the results of wind tunnel experiments. The numerical model was then employed to systematically examine the influences of wind direction, opening configuration and greenhouse length on the cross ventilation. In addition, an analytic model, based on inviscid flow assumption and mass conservation, was used to compute the ventilation rate. The results showed that the total ventilation rates of the multi-span greenhouses with open ridge vents were much larger than that of with closed ridge vents. The windward ridge vent (directly facing the wind direction when θ = 180°) can substantially increase the ventilation rate of multi-span monoslope greenhouses, as compared to the leeward ridge vent when wind direction θ = 0°. In other words, to take full advantage of the wind-driven ventilation the ridge vents of the greenhouses should directly face the prevailing wind direction. The ventilation rates can be reduced by adjusting the degree of opening and the number of the operable ridge vents.